Charging System - GMC G Service Manual

M Remove or Disconnect
1. Negative cable from the negative battery terminal.
2. Positive cable from the positive battery terminal.
3. Battery hold-down clamp.
4. Battery.
I W Inspect
1. Battery for damage.
2. Cables and connectors.
3. Carrier for damage or foreign objects.
• If damage is noted, find and correct the cause.
H Install or Connect
1. Battery into cleaned carrier.
2. Hold-down retainer or top bar, as equipped.
DESCRIPTION
The charging system consists of the battery, the gener­
ator, the regulator, and the charging system indicator lamp
circuitry. The generator supplies electrical power for charg­
ing the battery and operating accessories.
Two types of generators are used on these vehicles, the
SI generator with an external 2-terminal connector on the
regulator, and the CS generator with an external 4-terminal
connector on the regulator. The diagnostic tests for these
generators are different.
12-SI 100 AND 17-SI 100 GENERATORS (Figures 7, 8
and 9)
These generators are of the "Systems Integral" series
(generators with built-in regulator).
The solid state regulator components are enclosed into
a solid mold, and this unit, along with the brush holder
assembly, is attached to the slip ring end frame. The regu­
lator voltage setting cannot be adjusted.
The generator rotor bearings contain enough grease to
eliminate the need for periodic lubrication. Two brushes
carry current through the two slip rings to the field coil
mounted on the rotor, and under normal conditions will pro­
vide long periods of attention-free service.
The 12-SI has a "Y" stator and the 17-SI has a delta-
wound stator. The stator windings are assembled on the
inside of a laminated core that forms part of the generator
frame. A rectifier bridge connected to the stator windings
contains six diodes, and electrically changes the stator AC
voltages to a DC voltage which appears at the generator
output (BAT) terminal. Generator field current is supplied
through a diode trio which also is connected to the stator
windings. A capacitor or condenser, mounted in the end
frame, protects the rectifier bridge and diode trio from high
voltages, and suppresses radio noise.
SYSTEM
CHARGING
the generator assembly. For off-vehicle service, refer to the
1988 Light Duty Trucks Unit Repair Manual.
ENGINE ELECTRICAL 6D-7
H O Tighten
1. Retainer to 17 N«m (13 ft. lbs.).
2. Top bar to 3.5 N»m (30 in. lbs.) on batteries with
side terminals.
3. Top bar to 6.8 N«m (60 in. lbs.) on batteries with
top terminals.
3. Positive cable to the positive terminal.
4. Negative cable to the negative terminal.
I ^ l Tighten
• Top terminals to 17 N*m (13 ft. lbs.).
• Side terminals to 15 N»m (11 ft. lbs.).
No periodic maintenance or adjustment is required on
51. BAT Terminal
52. No. 1 Terminal
53. No. 2 Terminal
54. Field Ground Hole
Figure 7 — 12-SI Series 100 Generator
F-00013